Gas turbines have an outer casing body which is cooled from outside and which is protected on its inner side facing the hot turbine gases by a heat shield at a distance from the inner side. In this case, the air between heat shield and outer casing body serves as thermal insulation. In this respect, reference is made to the following documents: U.S. Pat. No. 4,121,768 A, U.S. Pat. No. 5,083,424 A, U.S. Pat. No. 5,697,213 A, U.S. Pat. No. 6,045,310 A, EP 0 224 817 A1, EP 0 724, 116 A2, EP 1 598 562 A1, GB 647 302 A and JP 2000335500 A.